1. Under the provisions of Articles 101(1) and 102(2) EPC, an Opposition Division cannot validly hold that an opposition must be rejected until it has assured itself that none of the grounds for opposition listed in Article 100 EPC preclude the maintenance of the European patent at issue. It may not confine its examination merely to the grounds expressly mentioned in the notice of opposition but must examine the facts of its own motion in accordance with Article 114(1) EPC.
2. A decision of an Opposition Division rejecting the opposition is not correctly reasoned within the meaning of the first sentence of Rule 68(2) EPC if, after giving the reasons why the Opposition Division, unlike the opponent, considers the subject- matter of the patent to be new, it fails to state the reasons why it considers that the subject-matter also involves an inventive step.

I. The Respondents are the proprietors of European patent No. 0 033 263 (application No. 81 400 060.0). The patent embodies ten claims with the only independent claim being worded as follows: "1. Spacer grid for a fuel assembly employed in a pressurised light water nuclear reactor comprising intersecting plates (19) forming a grid of rectangular units, in whose cells (7) the fuel rods (8) are transversely held, said rods constituting a bundle in which certain rods are replaced by guide tubes (10) ensuring, on the one hand, the mechanical integrity of the assembly and, on the other, guidance of the reactivity-control rods, the plates which constitute the walls of the cells carrying fuel rod support elements which extend into the interior of the cells and are of two types, one type being rigid members (13, 14) and the other type being springs (12), adapted to exercise transverse forces on the fuel rods, carried on the grid and disposed around the plates whereby each surface of each cell containing a rod carries an element of a type different from that carried on the opposite surface, characterised in that it comprises:

- over the greater part of the walls fitted with springs, double springs (12) comprising two active parts on either side of the wall in which the double spring is fitted, permitting symmetrical action of said spring on two different rods in the interior of two adjacent cells;

- on the other walls fitted with springs, simple springs (16) comprising a single active portion located in one of the two cells separated by the wall in which the spring is fitted, the other part which is not adapted to contact a fuel rod having at least one deformation zone (68), the two preceding parts having ends which are welded, and freely and slideably mounted with respect to the plate supporting them."

II. Kraftwerk Union Aktiengesellschaft, a company of which the Appellants are the successors in title, lodged opposition to the patent. In their notice of opposition dated 25 September 1986 they requested that the patent be revoked in its entirety and, in the alternative, that oral proceedings be held. They also mentioned that their opposition was based on Article 100(a) EPC and stated that the subject-matter of Claim 1 was entirely anticipated by the content of document DE-A-2 137 158 (document 1).

III. After the parties had submitted written observations on the question of whether the subject-matter of Claim 1 was anticipated by the content of document 1, they were summoned to attend oral proceedings by the Opposition Division. In the communication accompanying the summons to oral proceedings, dated 26 April 1988, the Opposition Division informed the parties that, in its opinion, the subject-matter of Claim 1 of the patent at issue was new, contrary to the Opponents' contention, and that since the Opponents had not expressly cited lack of inventive step as a ground of opposition, there was no need for it to rule on that issue.

IV. The oral proceedings convened by the Opposition Division were held on 6 June 1988. It appears from the minutes of the oral proceedings in the file that the line of argument pursued by the Opponents sought essentially to show that the differences between the subject- matter of Claim 1 and the content of document 1, as they were enumerated by the Opposition Division in the communication accompanying the summons to the oral proceedings, either were non-existent, resulted from features which did not provide sufficient information for a person skilled in the art to carry out the invention or were not disclosed in the documents of the application as filed, as required by Article 123(2) EPC. Those arguments were contested by the patent proprietors. At the close of the oral proceedings, the chairman of the Opposition Division ruled that the opposition should be rejected.

V. A written decision dated 8 August 1988 was subsequently notified to the parties. In the part of that decision relating to the statement of the facts and submissions, the Opposition Division stated that during the oral proceedings it had observed that the Opponents had contested the subject-matter of the patent solely from the point of view of its novelty within the meaning of Articles 52(1) and 54 EPC, and that it had therefore decided to confine its consideration of the objection pursuant to Article 100(a) to the aspect of novelty (page 4, third paragraph). Furthermore, in the part setting out the reasons for the decision the Opposition Division stated that "in accordance with the Opponents' request ... the Opposition Division considered the subject-matter of the patent solely from the point of view of novelty; the Opponents' argument was based on one document only ... which, it was claimed, anticipated that subject-matter in its entirety" (reasons, point 1). As regards the substance, the Opposition Division held, on the one hand, that the subject-matter of Claim 1 was new in relation to the state of the art disclosed in document 1 and that, on the other hand, the objections of impermissible extension and lack of clarity raised by the Opponents during the oral proceedings were unfounded. Accordingly, it decided to reject the opposition and maintain the European patent unamended (reasons, point 4).

VI. The Appellants (Opponents) appealed against that decision.

VII. In the Statement of Grounds, the Appellants requested that the decision under appeal be set aside, that the patent be revoked in its entirety and, in addition, that the appeal fee be reimbursed. Alternatively, they requested oral proceedings. For their part, the Respondents (patentees) requested that the appeal be dismissed.

VIII. In support of their requests, the Appellants point out in the first place that the notice of opposition dated 25 September 1986 was based expressly on Article 100(a) EPC, which refers to Articles 52 to 57 EPC, and therefore also, in particular, to Articles 52(1) and 56. Consequently, the grounds of opposition referred to in the notice of opposition include lack of inventive step. They argue, further, that the requirement that the EPO examine the facts of its own motion laid down in Article 114(1) EPC takes precedence over the possibility afforded to the EPO by Article 114(2) of disregarding facts or evidence which are not submitted in due time by the parties concerned (see decision T 156/84 of Technical Board of Appeal 3.4.1 dated 9 April 1987, OJ EPO 1988, 372). Consequently, the Opposition Division was not entitled to reject out of hand at the oral proceedings on 6 June 1988 the Opponents' submissions concerning lack of inventive step; its refusal to hear the Opponents' comments manifestly constituted a serious procedural violation justifying reimbursement of the appeal fee. Moreover, the Appellants consider that Claim 1 of the contested patent is contrary to the provisions of Article 123(2) EPC in so far as the feature, introduced in the course of the examination proceedings, according to which the claimed grid is employed in a "pressurised" light water nuclear reactor was not disclosed in the documents of the application as filed. In the Appellants' view, the fact that the fuel assembly originally described incorporates guide tubes does not necessarily imply that the reactor is cooled by pressurised light water. In that connection, it cites document US-A-3 802 995 (document 2), which, it appears from the file, does not seem to have been mentioned hitherto either in the opposition proceedings or in the examination proceedings. That document desribes a fuel assembly for a boiling water reactor which incorporates a tube for conducting the water, corresponding to the guide tube of the claimed apparatus. Lastly, the Appellants consider that the other features of Claim 1 are the result of an obvious combination of features known either from document 1 or from document cited in the introduction to the description of the contested patent.

IX. In their reply dated 8 March 1989 to the notice of appeal, the Respondents observe in the first place that the Appellants "challenge the propriety of the Opposition Division's action, at the oral proceedings held before it on 6 June 1988 in Munich, in refusing from the outset to enter into discussion on the subject of inventive step, in particular in connection with a new document". In that regard, they take the view that this is a difference of opinion between the Appellants and the EPO which it is for the latter to settle, but point out, however, that the notice of appeal plainly does not set out the circumstances which prevented the Appellants from submitting the late-filed documents earlier, although that is required according to the terms of Decision T 156/84, mentioned by the Appellants. The Respondents also contest the Appellants' submissions as to the alleged non-compliance of Claim 1 with the provisions of Article 123(2) EPC and to the alleged lack of inventive step of its subject-matter.

Reasons for the Decision

1. The appeal is admissible.

2. In addition to the features of Claim 1 of the application as filed, Claim 1 of the patent as granted also includes particulars to the effect that: (a) the nuclear reactor in which the claimed grid is used is a "pressurised light water" nuclear reactor; (b) the guide tubes ensure on the one hand the mechanical integrity of the assembly and, on the other hand, guidance of the reactivity-control rods; and (c) the part of the simple springs which is not adapted to contact a fuel rod has at least one deformation zone, the two parts having, moreover, ends which are welded and freely and slideably mounted with respect to the plate supporting them. As far as supplementary feature (a) is concerned, the documents of the application as filed expressly state that the claimed spacer grid may be used in a light water nuclear reactor (page 1, lines 6 and 7), but do not specify a pressurised reactor. Nevertheless, the Board cannot identify any valid reason for questioning the Respondents' statements to the effect that only nuclear reactors cooled by pressurised water have fuel assemblies comprising fuel rods in which certain rods are replaced by tubes for the guidance of control bars as described in the application filed. In particular, the boiling water reactor disclosed in document 2 cited by the Appellants in their notice of appeal comprises fuel assemblies (20) each of which is made up of fuel rods (21) and a central tube (41) through which water, and not control rods, can be passed for the purpose of moderating the reactor; control rods are in fact formed by components of cruciform section (13) located outside the fuel assemblies (column 4, lines 36 to 50; column 5, lines 54 to 60; figure 4). The other supplementary features of Claim 1 are either the outcome of specifying additionally the function of the guide tubes, which consists in guiding the control elements - a purely peripheral point - or explicitly supported by the description as filed (page 1, lines 19 to 23; page 16, lines 1 to 24 and 29 to 32; page 17, lines 14 to 17). For those reasons, the ground for opposition specified in Article 100(c) EPC does not preclude maintenance of the patent as granted. The same applies to the ground for opposition set out in Article 100(b) EPC, since, in the Board's opinion, the patent, taken as a whole, discloses the invention set out in Claim 1 sufficiently clearly and completely for it to be carried out by a person skilled in the art. Moreover, this point is no longer contested by the Appellants, since, as regards in particular their contention during the opposition proceedings that the expression "the greater part" was too vague, they themselves now take the view that a person skilled in the art could readily determine the number of double springs needed to support a given fuel assembly (page 4, second paragraph of appeal document).

3. Novelty In the Board's opinion, none of the documents representing the state of the art in the file disclose a spacer grid with all the features set out in Claim 1. In particular, the extremities of the two parts of the springs disclosed in document 1 are not mounted freely and slideably with respect to the plate supporting them, but on the contrary are fastened firmly to it as is expressly stated both in Claim 6 of that document ("fest verankert") and in its description (page 14, last line, "sicher befestigt"). In this connection, the Appellants refer in their appeal document (page 5, second paragraph) to a passage in document 1 to the effect that the support clips are mounted ("aufgesteckt") on internal flanges in order to form the spacer elements (D1, page 15, second paragraph). However, the most that can be inferred from that passage is that the clips can be put into place by sliding them over the edge of the corresponding flange, but not that they can slide freely until they have reached their final mounting position. For that reason itself, the subject-matter of Claim 1 is new within the meaning of Article 54 EPC. Moreover, the novelty of that subject-matter is no longer contested by the Appellants.

4. Inventive step Independently of the criticism raised by the Appellants in their appeal document with regard to the manner in which the Opposition Division conducted the proceedings, the Board has found that the decision under appeal rejecting the opposition includes a detailed statement of the reasons why the Opposition Division considered that the subject-matter of Claim 1 was new, but contains no comments on the inventive step involved by that subject-matter. The Board has therefore considered whether in those circumstances the decision under appeal satisfied the requirement for decisions to be reasoned which is set out in the first sentence of Rule 68(2) EPC.

4.1 According to Article 101(1) EPC, if the opposition is admissible, the Opposition Division must examine "whether the grounds for opposition laid down in Article 100" prejudice the maintenance of the European patent. In addition, Article 102(2) EPC provides that if the Opposition Division is of the opinion that "the grounds for opposition mentioned in Article 100" do not prejudice the maintenance of the patent unamended, it is to reject the opposition. The aforementioned provisions refer in the clearest possible manner to all the grounds for opposition set out in Article 100 EPC, and do not limit, expressly or by implication, the scope of the examination to be carried out by the Opposition Division merely to the grounds for opposition mentioned by the opponent in the notice of opposition pursuant to Rule 55(c) EPC. Moreover, if those provisions were to be construed in such a way as to confine the examination of the opposition to only such reasons as are expressly mentioned by the opponent it would conflict with the principle of examination by the EPO of its own motion enshrined in Article 114(1) EPC, under which the EPO is to examine the facts of its own motion and is not to be restricted in that examination to the facts, evidence and arguments provided by the parties or the relief sought. For the reasons given by this Board in Decision T 156/84, on which the Appellants also rely (point VIII above, 2nd paragraph), it is only after the EPO has examined the facts of its own motion pursuant to Article 114(1) EPC and concluded that they have no bearing on the decision to be reached that it can decide pursuant to Article 114(2) EPC to disregard facts or evidence which were not submitted in due time by the parties concerned (reasons, point 3). The Board therefore cannot follow on this point the opinion given by Board 3.3.1 in decision T 320/88 dated 29 August 1989 (not published) to the effect that the Opposition Division is not under any duty to consider the question of inventive step in the absence of any argument on that point from the opponent (reasons, point 3.1). In the Board's view an Opposition Division may not validly reject an opposition until it has assured itself that none of the grounds for opposition set out in Article 100 EPC preclude the maintenance of the patent in question.

4.2 Plainly, the foregoing conclusions do not signify that the reasons for the decision must set out all the reasons expressly and in detail why each of the grounds for opposition listed in Article 100 EPC does not preclude the maintenance of the patent. Accordingly, where it is clearly apparent from the particular circumstances of the case that certain grounds for opposition in no way call into question the maintenance of the patent, it may be fully justified on the ground of procedural economy not to mention those grounds in the decision rejecting the opposition. Such a situation may arise in particular in the case of certain grounds for opposition which manifestly have no bearing on the grounds raised by the opponent during the opposition proceedings or in the case of grounds which are manifestly inapplicable to the circumstances considered (lack of industrial application, or subject-matter of the patent extending beyond the content of the application within the meaning of Article 100(c) EPC where there has been no amendment of the application). Moreover, given that Article 114(2) EPC authorises the EPO to disregard facts or evidence having no bearing on the decision to be taken where they are not submitted in due time, it must be considered, a fortiori, that the EPO is likewise not bound to take account of such facts or evidence which have not been submitted by the parties. However, the fact that the novelty of the subject-matter of a patent is at issue in opposition proceedings generally implies that the subject-matter is at least relatively close to the state of the art as found. In addition, the concepts of novelty and inventive step as defined for example in the case law relating to the examination of the patentability of equivalent means or the determination of the implicit content of a disclosure do not enable an absolutely precise distinction to be drawn between those two criteria. Consequently, the mere fact that during the examination for novelty differences come to light between the subject-matter of the patent and the nearest state of the art does not generally mean that it can automatically be concluded that those differences are sufficient to prove that the subject- matter was not obvious, except perhaps in exceptional cases where, for example, it becomes apparent in the course of the examination for novelty that the nearest state of the art cited by the opponent was not in fact made available to the public before the date on which the application was filed or that it constituted a co-pending application for a European patent within the meaning of Article 54(3) EPC, which is not to be considered in deciding whether there has been an inventive step (Article 56, second sentence, EPC).

4.3 However, the Board has not ascertained the existence of such special circumstances in this case. On the contrary, although the Appellants set out in their notice of opposition only arguments intended to show that the subject- matter of the patent lacked novelty, they nonetheless stated that their opposition was based on Article 100(a) EPC, which covers all the conditions for patentability set out in Articles 52 to 57 EPC. In this connection, it must also be observed that where an opponent, even in error, considers that the subject-matter of the patent to which he has filed opposition is not new having regard to a given state of the art, this is because he has been unable to find any differences between the subject-matter of the patent and the subject-matter representing that state of the art. In such a case, he cannot reasonably be required also to submit argument on inventive step, since such argument could on the contrary only be based on the finding that certain differences existed and on the assessment of their obviousness. Moreover, in the present case, even if the wording of the notice of opposition suggested that the Opponents' challenge to the first claim was based only on novelty and that inventive step was raised therein only in connection with dependent Claims 2 to 10, at least the Opponents' second letter, dated 15 July 1987, shows that they were in fact aware of the existence of certain differences between the subject-matter described in document 1 and the subject-matter of Claim 1 of the contested patent, which they considered to be insignificant ("es ist unwesentlich, ob ...", "einzig wichtig ist ...") to the extent that they regarded them as having been impliedly disclosed by document 1 to any person skilled in the art. Furthermore, the mere fact that the Opponents cited only one document in their notice of opposition cannot be construed - as the Opposition Division seems to have done (point 1, first paragraph of the reasons for the decision) - as limiting their challenge solely to the question of novelty, since the inventive step implied by the subject-matter of a claim may very well be called into question on the basis of the teaching of one document alone, supplemented, for instance, by the knowledge generally held by a person skilled in the art. Consequently, in this case the Opposition Division should have considered whether or not, in the light of the document cited in the notice of opposition, the subject-matter of Claim 1 was obvious to a person skilled in the art within the meaning of Article 56 EPC, and given the reasons on which it based that conclusion. Accordingly, the Board considers that the Opposition Division has not stated reasons for its decision in accordance with the requirements of the first sentence of Rule 68(2) EPC and that, for that reason itself, the decision must be set aside.

5. In view of the fact that it is not apparent from the file that the Opposition Division already considered the question of the inventive step implied by the subject-matter of Claim 1, and in order not to deprive the parties of their right to a full examination of the opposition by two instances, the Board has decided to exercise its power under Article 111 EPC and remit the case to the Opposition Division for further prosecution.

6. The Board has reached the above conclusions without examining the justification of the Appellants' allegation that the Opposition Division refused from the outset to give them a hearing on questions relating to the inventive step of the subject-matter of the patent. In that connection, it cannot be established with certainty from the content of the file whether the Opposition Division did in fact actually debar the Appellants from presenting argument on the inventive step of the subject-matter of the patent or whether, after hearing that argument, the Division decided not to take it into account. Neither has the identity of the "new document" on which the Opposition Division, according to the Respondents, refused to allow discussion (point 1 of the Respondents' observations, dated 8 March 1989) been established. In view of the above conclusions, the Board considers that there is no point in continuing the examination of the file in order accurately to establish the facts and to rule on the relevance of the Appellants' criticism.

7. In the Board's view, the failure to comply with the provisions of the first sentence of Rule 68(2) EPC on stating reasons for decisions constitutes a serious procedural violation as a result of which it is equitable to reimburse the appeal fee, as requested by the Appellants.

8. Since the Board has therefore allowed the Appellants' main requests, their auxiliary request relating to the holding of oral proceedings no longer has any purpose.

ORDER

For these reasons it is decided that:

1. The decision under appeal is set aside.

2. The case is remitted to the Opposition Division for further prosecution.